This application report provides examples that illustrate the bit-transaction details of I²C commands used with TI's bq34xxx series and bq35xxx series battery fuel gauges. The first two examples provide detailed explanations of using I²C commands to read standard parameters and Control Subcommand parameters. The first example shows how to implement a standard fuel gauge command that interrogates the gauge for reading cell voltage. The second example shows the added bit transitions required to access a Control Subcommand, specifically requesting firmware version information. Other I²C commands can be executed in the same manner, using the methodology of these two examples. The final sections provide step-by-step examples using the bqStudio I²C Master Control Panel to read and write parameters from these gauges.